The subject matter of co-pending U.S. patent application Ser. No. 09/885,867, filed on Jun. 20, 2001, entitled xe2x80x9cControllable, Wearable MRI-Compatible Cardiac Pacemaker With Pulse Carrying Photonic Catheter And VOO Functionalityxe2x80x9d; co-pending U.S. patent application Ser. No. 09/885,868, filed on Jun. 20, 2001, entitled xe2x80x9cControllable, Wearable MRI-Compatible Cardiac Pacemaker With Power Carrying Photonic Catheter And VOO Functionalityxe2x80x9d; co-pending U.S. patent application Ser. No. 10/037,513, filed on Jan. 4, 2002, entitled xe2x80x9cOptical Pulse Generator For Battery Powered Photonic Pacemakers And Other Light Driven Medical Stimulation Equipmentxe2x80x9d; co-pending U.S. patent application Ser. No. 10/037,720, filed on Jan. 4, 2002, entitled xe2x80x9cOpto-Electric Coupling Device For Photonic Pacemakers And Other Opto-Electric Medical Stimulation Equipmentxe2x80x9d; co-pending U.S. patent application Ser. No. 09/943,216, filed on Aug. 30, 2001, entitled xe2x80x9cPulse width Cardiac Pacing Apparatusxe2x80x9d; co-pending U.S. patent application Ser. No. 09/964,095, filed on Sep. 26, 2001, entitled xe2x80x9cProcess for Converting Lightxe2x80x9d; and co-pending U.S. patent application Ser. No. 09/921,066, filed on Aug. 2, 2001, entitled xe2x80x9cMRI-Resistant Implantable Devicexe2x80x9d. The entire contents of each of the above noted co-pending U.S. patent application (Ser. Nos. 09/885,867; 09/885,868; 10/037,513; 10/037,720; 09/943,216; 09/964,095; and 09/921,066) are hereby incorporated by reference.
The present invention relates generally to an implantable device that is immune or hardened to electromagnetic insult or interference. More particularly, the present invention is directed to implantable systems that utilize fiber optic leads and other components to hardened or immune the systems from electromagnetic insult, namely magnetic-resonance imaging insult.
Magnetic resonance imaging (xe2x80x9cMRIxe2x80x9d) has been developed as an imaging technique adapted to obtain both images of anatomical features of human patients as well as some aspects of the functional activities of biological tissue. These images have medical diagnostic value in determining the state of the health of the tissue examined.
In an MRI process, a patient is typically aligned to place the portion of the patient""s anatomy to be examined in the imaging volume of the MRI apparatus. Such an MRI apparatus typically comprises a primary magnet for supplying a constant magnetic field (B0) which, by convention, is along the z-axis and is substantially homogeneous over the imaging volume and secondary magnets that can provide linear magnetic field gradients along each of three principal Cartesian axes in space (generally x, y, and z, or x1, x2 and X3, respectively). A magnetic field gradient (xcex94B0/xcex94xi) refers to the variation of the field along the direction parallel to B0 with respect to each of the three principal Cartesian axes, xi. The apparatus also comprises one or more RF (radio frequency) coils which provide excitation and detection of the MRI signal.
The use of the MRI process with patients who have implanted medical assist devices; such as cardiac assist devices or implanted insulin pumps; often presents problems. As is known to those skilled in the art, implantable devices (such as implantable pulse generators (IPGs) and cardioverter/defibrillator/pacemakers (CDPs)) are sensitive to a variety of forms of electromagnetic interference (EMI) because these enumerated devices include sensing and logic systems that respond to low-level electrical signals emanating from the monitored tissue region of the patient. Since the sensing systems and conductive elements of these implantable devices are responsive to changes in local electromagnetic fields, the implanted devices are vulnerable to external sources of severe electromagnetic noise, and in particular, to electromagnetic fields emitted during the magnetic resonance imaging (MRI) procedure. Thus, patients with implantable devices are generally advised not to undergo magnetic resonance imaging (MRI) procedures.
To more appreciate the problem, the use of implantable cardiac assist devices during a MRI process will be briefly discussed.
The human heart may suffer from two classes of rhythmic disorders or arrhythmias: bradycardia and tachyarrhythmia. Bradycardia occurs when the heart beats too slowly, and may be treated by a common implantable pacemaker delivering low voltage (about 3 V) pacing pulses.
The common implantable pacemaker is usually contained within a hermetically sealed enclosure, in order to protect the operational components of the device from the harsh environment of the body, as well as to protect the body from the device.
The common implantable pacemaker operates in conjunction with one or more electrically conductive leads, adapted to conduct electrical stimulating pulses to sites within the patient""s heart, and to communicate sensed signals from those sites back to the implanted device.
Furthermore, the common implantable pacemaker typically has a metal case and a connector block mounted to the metal case that includes receptacles for leads which may be used for electrical stimulation or which may be used for sensing of physiological signals. The battery and the circuitry associated with the common implantable pacemaker are hermetically sealed within the case. Electrical interfaces are employed to connect the leads outside the metal case with the medical device circuitry and the battery inside the metal case.
Electrical interfaces serve the purpose of providing an electrical circuit path extending from the interior of a hermetically sealed metal case to an external point outside the case while maintaining the hermetic seal of the case. A conductive path is provided through the interface by a conductive pin that is electrically insulated from the case itself.
Such interfaces typically include a ferrule that permits attachment of the interface to the case, the conductive pin, and a hermetic glass or ceramic seal that supports the pin within the ferrule and isolates the pin from the metal case.
A common implantable pacemaker can, under some circumstances, be susceptible to electrical interference such that the desired functionality of the pacemaker is impaired. For example, common implantable pacemaker requires protection against electrical interference from electromagnetic interference (EMI), defibrillation pulses, electrostatic discharge, or other generally large voltages or currents generated by other devices external to the medical device. As noted above, more recently, it has become crucial that cardiac assist systems be protected from magnetic-resonance imaging sources.
Such electrical interference can damage the circuitry of the cardiac assist systems or cause interference in the proper operation or functionality of the cardiac assist systems. For example, damage may occur due to high voltages or excessive currents introduced into the cardiac assist system.
Therefore, it is required that such voltages and currents be limited at the input of such cardiac assist systems, e.g., at the interface. Protection from such voltages and currents has typically been provided at the input of a cardiac assist system by the use of one or more zener diodes and one or more filter capacitors.
For example, one or more zener diodes may be connected between the circuitry to be protected, e.g., pacemaker circuitry, and the metal case of the medical device in a manner which grounds voltage surges and current surges through the diode(s). Such zener diodes and capacitors used for such applications may be in the form of discrete components mounted relative to circuitry at the input of a connector block where various leads are connected to the implantable medical device, e.g., at the interfaces for such leads.
However, such protection, provided by zener diodes and capacitors placed at the input of the medical device, increases the congestion of the medical device circuits, at least one zener diode and one capacitor per input/output connection or interface. This is contrary to the desire for increased miniaturization of implantable medical devices.
Further, when such protection is provided, interconnect wire length for connecting such protection circuitry and pins of the interfaces to the medical device circuitry that performs desired functions for the medical device tends to be undesirably long. The excessive wire length may lead to signal loss and undesirable inductive effects. The wire length can also act as an antenna that conducts undesirable electrical interference signals to sensitive CMOS circuits within the medical device to be protected.
Additionally, the radio frequency (RF) energy that is inductively coupled into the wire causes intense heating along the length of the wire, and at the electrodes that are attached to the heart wall. This heating may be sufficient to ablate the interior surface of the blood vessel through which the wire lead is placed, and may be sufficient to cause scarring at the point where the electrodes contact the heart. A further result of this ablation and scarring is that the sensitive node that the electrode is intended to pace with low voltage signals becomes desensitized, so that pacing the patient""s heart becomes less reliable, and in some cases fails altogether.
Another conventional solution for protecting the implantable medical device from electromagnetic interference is illustrated in FIG. 1. FIG. 1 is a schematic view of an implantable medical device 12 embodying protection against electrical interference. At least one lead 14 is connected to the implantable medical device 12 in connector block region 13 using an interface.
In the case where implantable medical device 12 is a pacemaker implanted in a body 10, the pacemaker 12 includes at least one or both of pacing and sensing leads represented generally as leads 14 to sense electrical signals attendant to the depolarization and repolarization of the heart 16, and to provide pacing pulses for causing depolarization of cardiac tissue in the vicinity of the distal ends thereof.
FIG. 2 more particularly illustrates the circuit that is used conventionally to protect from electromagnetic interference. As shown in FIG. 2, protection circuitry 15 is provided using a diode array component 30. The diode array consists of five zener diode triggered semiconductor controlled rectifiers (SCRs) with anti-parallel diodes arranged in an array with one common connection. This allows for a small footprint despite the large currents that may be carried through the device during defibrillation, e.g., 10 amps. The SCRs 20-24 turn on and limit the voltage across the device when excessive voltage and current surges occur.
As shown in FIG. 2, each of the zener diode triggered SCRs 20-24 is connected to an electrically conductive pin 25, 26, 28 and 29. Further, each electrically conductive pin 25, 26, 28 and 29 is connected to a medical device contact region 31, 32, 34 and 35 to be wire bonded to pads of a printed circuit board. The diode array component 30 is connected to the electrically conductive pins 25, 26, 28 and 29 via the die contact regions along with other electrical conductive traces of the printed circuit board.
Other attempts have been made to protect implantable devices from MRI fields. For example, U.S. Pat. No. 5,968,083 (to Ciciarelli et al.) describes a device adapted to switch between low and high impedance modes of operation in response to EMI insult. Furthermore, U.S. Pat. No. 6,188,926 (to Vock) discloses a control unit for adjusting a cardiac pacing rate of a pacing unit to an interference backup rate when heart activity cannot be sensed due to EMI.
Although, conventional medical devices provide some means for protection against electromagnetic interference, these conventional devices require much circuitry and fail to provide fail-safe protection against radiation produced by magnetic-resonance imaging procedures. Moreover, the conventional devices fail to address the possible damage that can be done at the tissue interface due to RF-induced heating, and they fail to address the unwanted heart stimulation that may result from RF-induced electrical currents.
Thus, it is desirable to provide protection against electromagnetic interference, without requiring much circuitry and to provide fail-safe protection against radiation produced by magnetic-resonance imaging procedures. Moreover, it is desirable to provide devices that prevent the possible damage that can be done at the tissue interface due to induced electrical signals and due to thermal tissue damage. Furthermore, it is desirable to provide to provide an effective means for transferring energy from one point in the body to another point without having the energy causing a detrimental effect upon the body.
A first aspect of the present invention is a cardiac assist system. The cardiac assist system includes a primary device housing; the primary device housing having a control circuit therein; a shielding formed around the primary device housing to shield the primary device housing and any circuits therein from electromagnetic interference; and a lead system to transmit and receive signals between a heart and the primary device housing.
A second aspect of the present invention is a cardiac assist system. The cardiac assist system includes a primary device housing; the primary device housing having a control circuit therein; a lead system to transmit and receive signals between a heart and the primary device housing; and a detection circuit, located in the primary device housing, to detect an electromagnetic interference insult upon the cardiac assist system. The control circuit places the cardiac assist system in an asynchronous mode upon detection of the electromagnetic interference insult by the detection system.
A third aspect of the present invention is a cardiac assist system. The cardiac assist system includes a primary device housing; the primary device housing having a control circuit therein; a shielding formed around the primary device housing to shield the primary device housing and any circuits therein from electromagnetic interference; a fiber optic based lead system to receive signals at the primary housing from a heart; and an electrical based lead system to transmit signals to the heart from the primary device housing.
A fourth aspect of the present invention is a cardiac assist system. The cardiac assist system includes a primary device housing; the primary device housing having a control circuit therein; a shielding formed around the primary device housing to shield the primary device housing and any circuits therein from electromagnetic interference; and a fiber optic based lead system to receive signals at the primary housing from a heart and to transmit signals to the heart from the primary device housing.
A fifth aspect of the present invention is a cardiac assist system for implanting in a body of a patient, the cardiac assist system comprising; a main module; a magnetic-resonance imaging-immune auxiliary module; a communication channel between the main module and the magnetic-resonance imaging-immune auxiliary module for the magnetic-resonance imaging-immune auxiliary module to detect failure of the main module; and a controller for activating the magnetic-resonance imaging-immune auxiliary module upon detection of failure of the main module.
A sixth aspect of the present invention is a cardiac assist system. The cardiac assist system includes a primary device housing including a power supply and a light source; the primary device housing having a control circuit therein; a shielding formed around the primary device housing to shield the primary device housing and any circuits therein from electromagnetic interference; a cardiac assist device associated with a heart; and a photonic lead system to transmit between the primary device housing and the cardiac assist device, both power and control signals in the form of light.
A further aspect of the present invention is a cardiac assist system. The cardiac assist system includes a primary device housing; the primary device housing having a first control circuit, therein, to perform synchronous cardiac assist operations; a secondary device housing having a second control circuit therein, to perform asynchronous cardiac assist operations; and a detection circuit, communicatively coupled to the first and second control circuits, to detect an electromagnetic interference insult upon the cardiac assist system. The first control circuit terminates synchronous cardiac assist operations and the second control circuit initiates asynchronous cardiac assist operations upon detection of the electromagnetic interference insult by the detection system.
A further aspect of the present invention is an implantable cable for transmission of a signal to and from a body tissue of a vertebrate. The implantable cable includes a fiber optic bundle having a surface of non-immunogenic, physiologically compatible material, the fiber optic bundle being capable of being permanently implanted in a body cavity or subcutaneously, the fiber optic bundle having a distal end for implantation at or adjacent to the body tissue and a proximal end. The proximal end is adapted to couple to and direct an optical signal source; the distal end is adapted to couple to an optical stimulator. The fiber optic bundle delivers an optical signal intended to cause an optical simulator located at the distal end to deliver an excitatory stimulus to a selected body tissue, the stimulus being causing the selected body tissue to function as desired.
A further aspect of the present invention is an implantable cable for transmission of a signal to and from a body tissue of a vertebrate. The implantable cable includes a fiber optic bundle having a surface of non-immunogenic, physiologically compatible material, the fiber optic bundle being capable of being permanently implanted in a body cavity or subcutaneously, the fiber optic bundle having a distal end for implantation at or adjacent to the body tissue and a proximal end. The proximal end is adapted to couple to an optical signal receiver, the distal end is adapted to couple to a sensor; the fiber optic bundle delivers an optical signal from a coupled sensor intended to cause an optical signal receiver coupled to the proximal end to monitor characteristics of a selected body tissue.
A further aspect of the present invention is an implantable cable for transmission of power to a body tissue of a vertebrate. The implantable cable consists of a fiber optic lead having a surface of non-immunogenic, physiologically compatible material and being capable of being permanently implanted in a body cavity or subcutaneously. The fiber optic lead has a proximal end adapted to couple to an optical portal, a coupled optical portal being able to receive light from a source external to the vertebrate, and a distal end adapted to couple to a photoelectric receiver, a coupled photoelectric receiver being able to convert light into electrical energy for use at the distal end.
A further aspect of the present invention is an implantable cable for the transmission of power to a body tissue of a vertebrate. The implantable cable consists of a fiber optic lead having a surface of non-immunogenic, physiologically compatible material and being capable of being permanently implanted in a body cavity or subcutaneously. The fiber optic lead has a distal end adapted to couple to a sensor, a coupled sensor being able to produce light signal based on a measured characteristic of a selected body tissue region, and a proximal end being adapted to couple to an optical portal, the optical portal being able to receive light produced by a coupled sensor.
A further aspect of the present invention is an implantable cable for the transmission of power to a body tissue of a vertebrate. The implantable cable consists of a fiber optic lead having a surface of non-immunogenic, physiologically compatible material and being capable of being permanently implanted in a body cavity or subcutaneously. The fiber optic lead has a proximal end being adapted to be coupled to an optical portal, a coupled optical portal being able to receive light from a light source, and a distal end being adapted to be coupled to a photoelectric receiver, a coupled photoelectric receiver being able to convert light into electrical energy for use at the distal end.
A further aspect of the present invention is an implantable cable for the transmission of power to a body tissue of a vertebrate. The implantable cable includes a fiber optic lead having a cylindrical surface of non-immunogenic, physiologically compatible material and being capable of being permanently implanted in a body cavity or subcutaneously. The fiber optic lead has a proximal end coupled to an electro-optical source; the electro-optical source converts electrical energy into light energy. The distal end coupled to a photoelectric receiver, the photoelectric receiver converts light energy into electrical energy for use at the distal end.
A further aspect of the present invention is a cardiac assist system. The cardiac assist system includes a primary device housing, having a control circuit therein, and a fiber optic based communication system to transmit and receive signals between a desired anatomical cardiac tissue region and the primary device housing.
A still further aspect of the present invention is a tissue invasive device. The tissue invasive device includes a primary device housing, having a control circuit therein and a fiber optic based communication system to transmit and receive signals between a selected tissue region and the primary device housing.
A further aspect of the present invention is a cardiac assist system. The cardiac assist system includes a primary device housing, having a control circuit therein, and a lead system to transmit and receive signals between a desired anatomical cardiac tissue region and the primary device housing. The lead system includes a sensing and stimulation system at an epicardial-lead interface with the desired anatomical cardiac tissue region. The sensing and stimulation system includes optical sensing components to detect physiological signals from the desired anatomical cardiac tissue region.
A still further aspect of the present invention is a tissue invasive device. The tissue invasive device includes a primary device housing, having a control circuit therein, and a lead system to transmit and receive signals between a selected tissue region and the primary device housing. The lead system includes a sensing and stimulation system at an interface with the selected tissue region. The sensing and stimulation system includes optical sensing components to detect physiological signals from the selected tissue region.
A further aspect of the present invention is a cardiac assist system. The cardiac assist system consists of a primary device housing, having a control circuit therein, and a lead system to transmit and receive signals between a desired anatomical cardiac tissue region and the primary device housing. The lead system includes a sensing and stimulation system at an epicardial-lead interface with the desired anatomical cardiac tissue region; the sensing and stimulation system includes optical sensing components to detect physiological signals from the desired anatomical cardiac tissue region and electrical sensing components to detect physiological signals from the desired anatomical cardiac tissue region.
A still further aspect of the present invention is a tissue invasive device. The tissue invasive device includes a primary device housing, having a control circuit therein, and a lead system to transmit and receive signals between a selected tissue region and the primary device housing. The lead system includes a sensing and stimulation system at an epicardial-lead interface with the selected tissue region. The sensing and stimulation system includes optical sensing components to detect physiological signals from the selected tissue region and electrical sensing components to detect physiological signals from the selected tissue region.
A further aspect of the present invention is a transducer system to transmit and receive signals between a selected tissue region and a tissue invasive device. The transducer system consists of an electrical lead and an electrode located on an end of the electrical lead having an anti-antenna geometrical shape, the anti-antenna geometrical shape preventing the electrode from picking up and conducting stray electromagnetic interference.
A further aspect of the present invention is a cardiac assist transducer system to transmit and receive signals between a cardiac tissue region and a cardiac assist device. The cardiac assist transducer system consists of an electrical lead to deliver electrical pulses to the cardiac tissue region; and an electrode located on an end of the electrical lead having an anti-antenna geometrical shape, the anti-antenna geometrical shape preventing the electrode from picking up and conducting stray electromagnetic interference.
A still further aspect of the present invention is a cardiac assist system. The cardiac assist system consists of a primary device housing; the primary device housing has a control circuit therein; a lead system to transmit and receive signals between a heart and the primary device housing; a shielding formed around the lead system to shield the lead system from electromagnetic interference; and a biocompatible material formed around the shielding.
A further aspect of the present invention is a cardiac assist system. The cardiac assist system consists of a primary device housing; the primary device housing has a control circuit therein; a fiber optic EMI-immune lead system to transmit and receive signals between a heart and the primary device housing; and a biocompatible material formed around the fiber optic EMI-immune lead system.
A further aspect of the present invention is a cardiac assist system. The cardiac assist system consists of a primary device housing; the primary device housing has a control circuit therein; an optical-electrical lead system to transmit and receive signals between a heart and the primary device housing; a shielding formed around the optical-electrical lead system to shield the optical-electrical lead system from electromagnetic interference; and a biocompatible material formed around the shielding.
A further aspect of the present invention is a tissue invasive device. The tissue invasive device consists of a primary device housing; the primary device housing has a control circuit therein; a lead system to transmit and receive signals between a selected tissue region and the primary device housing; a shielding formed around the lead system to shield the lead system from electromagnetic interference; and a biocompatible material formed around the shielding.
A still further aspect of the present invention is a tissue invasive device. The tissue invasive device consists of a primary device housing; the primary device housing having a control circuit therein; a fiber optic EMI-immune lead system to transmit and receive signals between a selected tissue region and the primary device housing; and a biocompatible material formed around the fiber optic EMI-immune lead system.
A further aspect of the present invention is a tissue invasive device. The tissue invasive device consists of a primary device housing; the primary device housing having a control circuit therein; an optical-electrical lead system to transmit and receive signals between a selected tissue region and the primary device housing; a shielding formed around the optical-electrical lead system to shield the optical-electrical lead system from electromagnetic interference; and a biocompatible material formed around the shielding.
A further aspect of the present invention is a cardiac assist system. The cardiac assist system consists of a primary device housing; the primary device housing has a control circuit therein; a shielding formed around the primary device housing to shield the primary device housing and any circuits therein from electromagnetic interference; and a biocompatible material formed around the shielding.
A further aspect of the present invention is a tissue invasive device. The tissue invasive device consists of a primary device housing; the primary device housing having a control circuit therein; a shielding formed around the primary device housing to shield the primary device housing and any circuits therein from electromagnetic interference; and a biocompatible material formed around the shielding.
A further aspect of the present invention is a cardiac assist system. The cardiac assist system consists of a primary device housing; the primary device housing having a control circuit therein; a shielding formed around the primary device housing to shield the primary device housing and any circuits therein from electromagnetic interference; a biocompatible material formed around the shielding; and a detection circuit, located in the primary device housing, to detect an electromagnetic interference insult upon the cardiac assist system. The control circuit will place the cardiac assist system in an asynchronous mode upon detection of the electromagnetic interference insult by the detection system.
A still further aspect of the present invention is a tissue invasive device. The tissue invasive device consists of a primary device housing; the primary device housing has a control circuit therein operating in a first mode. A shielding formed around the primary device housing to shield the primary device housing and any circuits therein from electromagnetic interference; a biocompatible material formed around the shielding; and a detection circuit, located in the primary device housing, to detect an electromagnetic interference insult upon the tissue invasive device. The control circuit places the tissue invasive device in a second mode upon detection of the electromagnetic interference insult by the detection system.
A further aspect of the present invention is a cardiac assist system. The cardiac assist system consists of a primary device housing having a first control circuit, therein, to perform synchronous cardiac assist operations; a first shielding formed around the primary device housing to shield the primary device housing and any circuits therein from electromagnetic interference; a first biocompatible material formed around the first shielding; a secondary device housing having a second control circuit, therein, to perform asynchronous cardiac assist operations; a second shielding formed around the secondary device housing to shield the secondary device housing and any circuits therein from electromagnetic interference; a second biocompatible material formed around the second shielding; and a detection circuit, communicatively coupled to the first and second control circuits, to detect an electromagnetic interference insult upon the cardiac assist system. The first control circuit terminates synchronous cardiac assist operations and the second control circuit initiates asynchronous cardiac assist operations upon detection of the electromagnetic interference insult by the detection system.
A still further aspect of the present invention is a cardiac assist system for implanting in a body of a patient. The cardiac assist system consists of a main module; a first shielding formed around the main module to shield the main module and any circuits therein from magnetic-resonance imaging interference; a first biocompatible material formed around the first shielding; a magnetic-resonance imaging-immune auxiliary module; a second shielding formed around the magnetic-resonance imaging-immune auxiliary module to shield the magnetic-resonance imaging-immune auxiliary module and any circuits therein from magnetic-resonance imaging interference; a second biocompatible material formed around the second shielding; a communication channel between the main module and the magnetic-resonance imaging-immune auxiliary module for the magnetic-resonance imaging-immune auxiliary module to detect failure of the main module; and a controller for activating the magnetic-resonance imaging-immune auxiliary module upon detection of failure of the main module.
A further aspect of the present invention is a cardiac assist system for implanting in the body of a patient. The cardiac assist system consists of a main module; a first biocompatible material formed around the main module; an magnetic-resonance imaging-hardened auxiliary module; a shielding formed around the magnetic-resonance imaging-hardened auxiliary module to shield the magnetic-resonance imaging-hardened auxiliary module and any circuits therein from magnetic-resonance imaging interference; a second biocompatible material formed around the second shielding; and a communication channel between the main module and the magnetic-resonance imaging-hardened auxiliary module. The magnetic-resonance imaging-hardened auxiliary module detecting, through the communication channel, failure of the main module; the magnetic-resonance imaging-hardened auxiliary module including a controller for activating the magnetic-resonance imaging-hardened auxiliary module upon detection of failure of the main module.
A further aspect of the present invention is a cardiac assist device. The cardiac assist device consists of a primary device housing; the primary device housing having a control circuit therein; a shielding formed around the primary device housing to shield the primary device housing and any circuits therein from electromagnetic interference; a lead system to transmit and receive signals between a selected cardiac tissue region and the primary device housing; a switch to place the control circuitry into a fixed-rate mode of operation; an acoustic sensor to sense a predetermined acoustic signal. The switch places the control circuitry into a fixed-rate mode of operation when the acoustic sensor senses the predetermined acoustic signal.
A further aspect of the present invention is a cardiac assist system. The cardiac assist system includes a primary device housing; the primary device housing having a control circuit therein; a shielding formed around the primary device housing to shield the primary device housing and any circuits therein from electromagnetic interference; a lead system to transmit and receive signals between a selected cardiac tissue region and the primary device housing; a switch to place the control circuitry into a fixed-rate mode of operation; a near infrared sensor to sense a predetermined near infrared signal; the switch placing the control circuitry into a fixed-rate mode of operations when the near infrared sensor senses the predetermined near infrared signal.
A still further aspect of the present invention is an implantable cable for the transmission of signals to and from a body tissue of a vertebrate. The implantable cable consists of a fiber optic lead having a surface of non-immunogenic, physiologically compatible material and being capable of being permanently implanted in a body cavity or subcutaneously; the fiber optic lead having a distal end for implantation at or adjacent to the body tissue and a proximal end; the fiber optic lead including a first optical fiber and a second optical fiber; the first optical fiber having, a proximal end coupled to an optical signal source, and a distal end coupled to an optical stimulator. The optical signal source generating an optical signal intended to cause the optical stimulator located at a distal end to deliver an excitatory stimulus to a selected body tissue, the stimulus causing the selected body tissue to function as desired. The second optical fiber having a distal end coupled to a sensor, and a proximal end coupled to a device responsive to an optical signal delivered by the second optical fiber; the sensor generating an optical signal to represent a state of a function of the selected body tissue to provide feedback to affect the activity of the optical signal source.
A further aspect of the present invention is an implantable cable for the transmission of signals to and from a body tissue of a vertebrate. The implantable cable includes a fiber optic lead having a surface of non-immunogenic, physiologically compatible material and being capable of being permanently implanted in a body cavity or subcutaneously; the fiber optic lead having a distal end for implantation at or adjacent to the body tissue and a proximal end; the proximal end of the fiber optic lead being coupled to an optical signal source and an optical device. The distal end of the fiber optic lead being coupled to an optical stimulator and a sensor; the optical signal source generating an optical signal intended to cause the optical stimulator located at a distal end to deliver an excitatory stimulus to a selected body tissue, the stimulus being causing the selected body tissue to function as desired. The optical device being responsive to an optical signal generated by the sensor, the optical signal generated by the sensor rep representing a state of a function of the selected body tissue to provide feedback to affect the activity of the optical signal source.
A further aspect of the present invention is a cardiac assist system. The cardiac assist system includes a primary device housing including a power supply and a light source; the primary device housing having a control circuit therein; a shielding formed around the primary device housing to shield the primary device housing and any circuits therein from electromagnetic interference; a cardiac assist device associated with a heart; a photonic lead system to transmit between the primary device housing and the cardiac assist device, both power and control signals in the form of light; a photoresponsive device to convert the light transmitted by the photonic lead system into electrical energy and to sense variations in the light energy to produce control signals; a charge accumulating device to receive and store the electrical energy produced by the photoresponsive device; and a discharge control device, responsive to the control signals, to direct the stored electrical energy from the charge accumulating device to the cardiac assist device associated with the heart.
A further aspect of the present invention is a tissue implantable device. The tissue implantable device includes a primary device housing including a power supply and a light source; the primary device housing having a control circuit therein; a shielding formed around the primary device housing to shield the primary device housing and any circuits therein from electromagnetic interference; a tissue interface device associated with a distinct tissue region; a photonic lead system to transmit between the primary device housing and the tissue interface device, both power and control signals in the form of light; a photoresponsive device to convert the light transmitted by the photonic lead system into electrical energy and to sense variations in the light energy to produce control signals; a discharge control device, responsive to the control signals, to direct the stored electrical energy from the charge accumulating device to the tissue interface device associated with a distinct tissue region.
A further aspect of the present invention is a tissue implantable device. The tissue implantable device includes a primary device housing; the primary device housing having a control circuit therein; a shielding formed around the primary device housing to shield the primary device housing and any circuits therein from electromagnetic interference; a lead system to transmit and receive signals between a tissue region of concern and the primary device housing; and a detection circuit to detect a phase timing of an external electromagnetic field; the control circuit altering its operations to avoid interfering with the detected external electromagnetic field.
A still further aspect of the present invention is a method for preventing a tissue implantable device failure during magnetic resonance imaging. The method includes determining a quiet period for a tissue implantable device and generating a magnetic resonance imaging pulse during a quiet period of the tissue implantable device.
A further aspect of the present invention is a method for preventing a tissue implantable device failure due to an external electromagnetic field source. The method includes detecting a phase timing of an external electromagnetic field and altering operations of the tissue implantable device to avoid interfering with the detected external electromagnetic field.
A further aspect of the present invention is a method for preventing a tissue implantable device failure during magnetic resonance imaging. The method includes detecting a phase timing of an external magnetic resonance imaging pulse field and altering operations of the tissue implantable device to avoid interfering with the detected external magnetic resonance imaging pulse field.
A further aspect of the present invention is a cardiac assist system for implanting in the body of a patient. The cardiac assist system includes a main module; an magnetic-resonance imaging-hardened auxiliary module; and a communication channel between the main module and the magnetic-resonance imaging-hardened auxiliary module; the magnetic-resonance imaging-hardened auxiliary module detecting, through the communication channel, failure of the main module; the magnetic-resonance imaging-hardened auxiliary module including a controller for activating the auxiliary module upon detection of failure of the main module.
A further aspect of the present invention is a signaling system for a two-module implantable medical device having a main module and an auxiliary module. The signaling system consists of signaling means in the main module for generating a signal to the auxiliary module, the signal representing a status of the main module or an instruction for the auxiliary module to activate; sensing means in the auxiliary module, in response to the signal from the signaling means, for determining if the auxiliary module should activate; and a switch to activate the auxiliary module when the sensing means determines that the signal from the signaling means indicates that the auxiliary module should activate.
A further aspect of the present invention is a cardiac assist system. The cardiac assist system includes a primary device housing; the primary device housing having a control circuit therein; a shielding formed around the primary device housing to shield the primary device housing and any circuits therein from electromagnetic interference; and a lead system to transmit and receive signals between a heart and the primary device housing; the control circuitry including an oscillator and amplifier operating at an amplitude level above that of an induced signal from a magnetic-resonance imaging field.
A still further aspect of the present invention is a cardiac assist system. The cardiac assist system includes a primary device housing; the primary device housing having a control circuit therein; a shielding formed around the primary device housing to shield the primary device housing and any circuits therein from electromagnetic interference; a lead system to transmit and receive signals between a heart and the primary device housing; a switch to place the control circuitry into a fixed-rate mode of operation; a changing magnetic field sensor to sense a change in magnetic field around the primary housing, the switch placing the control circuitry into a fixed-rate mode of operation when the changing magnetic field sensor senses a predetermined encoded changing magnetic field.
A further aspect of the present invention is an electromagnetic radiation immune tissue invasive delivery system. The electromagnetic radiation immune tissue invasive delivery system includes a photonic lead having a proximal end and a distal end; a storage device, located at the proximal end of the photonic lead, to store a therapeutic substance to be introduced into a tissue region; a delivery device to delivery a portion of the stored therapeutic substance to a tissue region; a light source, in the proximal end of the photonic lead, to produce a first light having a first wavelength and a second light having a second wavelength; a wave-guide between the proximal end and distal end of the photonic lead; a bio-sensor, in the distal end of the photonic lead, to sense characteristics of a predetermined tissue region; a distal sensor, in the distal end of the photonic lead, to convert the first light into electrical energy and, responsive to the bio-sensor, to reflect the second light back the proximal end of the photonic lead such that a characteristic of the second light is modulated to encode the sensed characteristics of the predetermined tissue region; a proximal sensor, in the proximal end of the photonic lead, to convert the modulated second light into electrical energy; and a control circuit, in response to the electrical energy from the proximal sensor, to control an amount of the stored therapeutic substance to be introduced into the tissue region.
A further aspect of the present invention is an electromagnetic radiation immune tissue invasive delivery system. The electromagnetic radiation immune tissue invasive delivery system includes a photonic lead having a proximal end and a distal end; a storage device, located at the proximal end of the photonic lead, to store a therapeutic substance to be introduced into a tissue region; a delivery device to deliver a portion of the stored therapeutic substance to a tissue region; a light source, in the proximal end of the photonic lead, to produce a first light having a first wavelength and a second light having a second wavelength; a wave-guide between the proximal end and distal end of the photonic lead; a bio-sensor, in the distal end of the photonic lead, to sense characteristics of a predetermined tissue region; a distal sensor, in the distal end of the photonic lead, to convert the first light into electrical energy and, responsive to the bio-sensor, to emit a second light having a second wavelength to proximal end of the photonic lead such that a characteristic of the second light is modulated to encode the sensed characteristics of the predetermined tissue region; a proximal sensor, in the proximal end of the photonic lead, to convert the modulated second light into electrical energy; and a control circuit, in response to the electrical energy from the proximal sensor, to control an amount of the stored therapeutic substance to be introduced into the tissue region.
A further aspect of the present invention is an electromagnetic radiation immune tissue invasive stimulation system. The electromagnetic radiation immune tissue invasive stimulation system includes a photonic lead having a proximal end and a distal end; a light source, in the proximal end of the photonic lead, to produce a first light having a first wavelength; a wave-guide between the proximal end and distal end of the photonic lead; a distal sensor, in the distal end of the photonic lead, to convert the first light into electrical energy into control signals; an electrical energy storage device to store electrical energy; and a control circuit, in response to the control signals, to cause a portion of the stored electrical energy to be delivered to a predetermined tissue region.
A further aspect of the present invention is an electromagnetic radiation immune tissue invasive sensing system. The electromagnetic radiation immune tissue invasive sensing system includes a photonic lead having a proximal end and a distal end; a light source, in the proximal end of the photonic lead, to produce a first light having a first wavelength; a wave-guide between the proximal end and distal end of the photonic lead; a distal sensor, in the distal end of the photonic lead, to convert the first light into electrical energy into control signals; an electrical energy storage device to store electrical energy; and a bio-sensor, in the distal end of the photonic lead, to sense a characteristic of a predetermined tissue region. The light source, in the proximal end of the photonic lead, produces a second light having a second wavelength. The distal sensor, in the distal end of the photonic lead and responsive to the bio-sensor, reflects the second light back the proximal end of the photonic lead such that a characteristic of the second light is modulated to encode the sensed characteristic of the predetermined tissue region.
A still further aspect of the present invention is an electromagnetic radiation immune tissue invasive sensing system. The electromagnetic radiation immune tissue invasive sensing system includes a photonic lead having a proximal end and a distal end; a light source, in the proximal end of the photonic lead, to produce a first light having a first wavelength and a second light having a second wavelength; a wave-guide between the proximal end and the distal end of the photonic lead; a bio-sensor, in the distal end of the photonic lead, to sense characteristics of a predetermined tissue region; and a distal sensor, in the distal end of the photonic lead, to convert the first light into electrical energy and, responsive to the bio-sensor, to reflect the second light back the proximal end of the photonic lead such that a characteristic of the second light is modulated to encode the sensed characteristics of the predetermined tissue region.
A further aspect of the present invention is an electromagnetic radiation immune tissue invasive sensing system. The electromagnetic radiation immune tissue invasive sensing system includes a photonic lead having a proximal end and a distal end; a light source, in the proximal end of the photonic lead, to produce a first light having a first wavelength; a wave-guide between the proximal end and distal end of the photonic lead; a bio-sensor, in the distal end of the photonic lead, to sense characteristics of a predetermined tissue region; and a distal sensor, in the distal end of the photonic lead, to convert the first light into electrical energy and, responsive to the bio-sensor, to emit a second light having a second wavelength to proximal end of the photonic lead such that a characteristic of the second light is modulated to encode the sensed characteristics of the predetermined tissue region.
A further aspect of the present invention is a photonic lead system. The photonic lead system includes a photonic lead having a distal end and a proximal end; and a magnetic radiation coil, located in the distal end, to detect characteristics of magnetic radiation of a predetermined nature.
A still further aspect of the present invention is an electromagnetic radiation immune sensing system. The electromagnetic radiation immune sensing system includes a photonic lead having a proximal end and a distal end; a light source, in the proximal end of the photonic lead, to produce a first light having a first wavelength and a second light having a second wavelength; a wave-guide between the proximal end and distal end of the photonic lead; a biosensor, in the distal end of the photonic lead, to measure changes in an electric field located outside a body, the electric field being generated by the shifting voltages on a body""s skin surface; and a distal sensor, in the distal end of the photonic lead, to convert the first light into electrical energy and, responsive to the bio-sensor, to reflect the second light back the proximal end of the photonic lead such that a characteristic of the second light is modulated to encode the measured changes in the electric field.
A further aspect of the present invention is an electromagnetic radiation immune sensing system. The electromagnetic radiation immune sensing system includes a photonic lead having a proximal end and a distal end; a light source, in the proximal end of the photonic lead, to produce a first light having a first wavelength; a wave-guide between the proximal end and distal end of the photonic lead; a bio-sensor, in the distal end of the photonic lead, to measure changes in an electric field located outside a body, the electric field being generated by the shifting voltages on a body""s skin surface; and a distal sensor, in the distal end of the photonic lead, to convert the first light into electrical energy and, responsive to the bio-sensor, to emit a second light having a second wavelength to proximal end of the photonic lead such that a characteristic of the second light is modulated to encode the measured changes in the electric field.
A further aspect of the present invention is a cardiac assist system. The cardiac assist system includes a primary device housing, the primary device housing having a control circuit therein; a shielding formed around the primary device housing to shield the primary device housing and any circuits therein from electromagnetic interference; a lead system to transmit and receive signals between a heart and the primary device housing; a switch to place the control circuitry into a fixed-rate mode of operation; and a changing magnetic field sensor to sense a change in magnetic field around the primary housing. The switch causes the control circuitry to turn-off and cease operation when the changing magnetic field sensor senses a predetermined encoded changing magnetic field.
A further aspect of the present invention is an electromagnetic radiation immune tissue invasive energy transfer system. The electromagnetic radiation immune tissue invasive energy transfer system includes a photonic lead having a proximal end and a distal end; a light source, at the proximal end of the photonic lead; a wave-guide between the proximal end and distal end of the photonic lead; a radiation scattering medium at the distal end of the photonic lead to receive radiation from the wave-guide; and a plurality of sensors to receive scattered radiation from the radiation scattering medium and convert the received scattered radiation into electrical energy.
A further aspect of the present invention is an electromagnetic radiation immune tissue invasive energy transfer system. The electromagnetic radiation immune tissue invasive energy transfer system includes a photonic lead having a proximal end and a distal end; a light source, at the proximal end of the photonic lead; a first wave-guide between the proximal end and distal end of the photonic lead; a second wave-guide, having a plurality of beam splitters therein at the distal end of the photonic lead to receive radiation from the first wave-guide; and a plurality of sensors to receive radiation from the beam splitters in the second wave-guide and convert the received radiation into electrical energy.
A further aspect of the present invention is an electromagnetic radiation immune tissue invasive energy transfer system. The electromagnetic radiation immune tissue invasive energy transfer system includes a photonic lead having a proximal end and a distal end; a light source, at the proximal end of the photonic lead; a wave-guide between the proximal end and distal end of the photonic lead; and a plurality of stacked sensors to receive radiation from the wave-guide and convert the received radiation into electrical energy. Each sensor absorbs a fraction of radiation incident upon the stack of sensors.
A further aspect of the present invention is an electromagnetic radiation immune tissue invasive energy transfer system. The electromagnetic radiation immune tissue invasive energy transfer system includes a photonic lead having a proximal end and a distal end; a light source, at the proximal end of the photonic lead; a wave-guide between the proximal end and distal end of the photonic lead; and a plurality of concentric sensors to receive radiation from the wave-guide and convert the received radiation into electrical energy. Each concentric sensors absorbs a fraction of radiation from said wave-guide.
A further aspect of the present invention is an electromagnetic radiation immune tissue invasive energy transfer system. The electromagnetic radiation immune tissue invasive energy transfer system includes a photonic lead having a proximal end and a distal end; a light source, at the proximal end of the photonic lead; a wave-guide between the proximal end and distal end of the photonic lead; a sensor to receive radiation from the wave-guide and convert the received radiation into electrical energy; and a plurality of switchable capacitors connected in parallel to an output of the sensor to enable simultaneous charging of the capacitors.
A farther aspect of the present invention is an electromagnetic radiation immune tissue invasive energy transfer system. The electromagnetic radiation immune tissue invasive energy transfer system includes a photonic lead having a proximal end and a distal end; a light source, at the proximal end of the photonic lead; a wave-guide between the proximal end and distal end of the photonic lead; a sensor to receive radiation from the wave-guide and convert the received radiation into electrical energy; a control circuit connected to an output of the sensor; and a plurality of switchable capacitors connected to the control circuit.
A further aspect of the present invention is an electromagnetic radiation immune tissue invasive energy transfer system. The electromagnetic radiation immune tissue invasive energy transfer system includes a photonic lead having a proximal end and a distal end; a light source, at the proximal end of the photonic lead; a wave-guide between the proximal end and distal end of the photonic lead; a sensor to receive radiation from the wave-guide and convert the received radiation into electrical energy; and a plurality of switchable capacitors connected to an output of the sensor to enable sequential charging of the capacitors with a pre-determined pulse intensity and duration.
A further aspect of the present invention is an electromagnetic radiation immune tissue invasive energy transfer system. The electromagnetic radiation immune tissue invasive energy transfer system includes a light source; a radiation beam splitter having multiple beam splitters; a plurality of wave-guides, each wave-guide receiving radiation from a beam splitter; and a plurality of sensors, each sensor receiving radiation from one of the plurality of wave-guides to convert the received radiation into electrical energy.
A further aspect of the present invention is a tissue invasive photonic system. The tissue invasive photonic system includes a photonic lead having a proximal end and a distal end; a light source, in the proximal end of the photonic lead, to produce a first light having a first wavelength and a second light having a second wavelength; a wave-guide between the proximal end and distal end of the photonic lead; a radiation scattering medium at the distal end of the photonic lead to receive radiation from the wave-guide; a plurality of power sensors to receive scattered radiation from the radiation scattering medium and convert the received scattered radiation into electrical energy; a bio-sensor, in the distal end of the photonic lead, to sense characteristics of a predetermined tissue region; and a distal emitter, in the distal end of the photonic lead and responsive to the bio-sensor, to emit a second light having a second wavelength to proximal end of the photonic lead such that a characteristic of the second light is modulated to encode the sensed characteristics of the predetermined tissue region.
A further aspect of the present invention is a tissue invasive photonic system. The tissue invasive photonic system includes a photonic lead having a proximal end and a distal end; a light source, in the proximal end of the photonic lead, to produce a first light having a first wavelength and a second light having a second wavelength; a first wave-guide between the proximal end and distal end of the photonic lead; a second wave-guide, having a plurality of power beam splitters therein at the distal end of the photonic lead to receive and reflect the first light from the first wave-guide; a plurality of power sensors to receive the first light from the power beam splitters in the second wave-guide and convert the received first light into electrical energy; a bio-sensor, in the distal end of the photonic lead, to sense characteristics of a predetermined tissue region; and a distal emitter, in the distal end of the photonic lead and responsive to the bio-sensor, to emit a second light having a second wavelength to proximal end of the photonic lead such that a characteristic of the second light is modulated to encode the sensed characteristics of the predetermined tissue region.
A further aspect of the present invention is a tissue invasive photonic system. The tissue invasive photonic system includes a photonic lead having a proximal end and a distal end; a light source, in the proximal end of the photonic lead, to produce a first light having a first wavelength and a second light having a second wavelength; a wave-guide between the proximal end and distal end of the photonic lead; a plurality of power sensors to receive the first light from the wave-guide and convert the received first light into electrical energy, each power sensor absorbing a fraction of the received first light; a bio-sensor, in the distal end of the photonic lead, to sense characteristics of a predetermined tissue region; and a distal emitter, in the distal end of the photonic lead and responsive to the bio-sensor, to emit a second light having a second wavelength to proximal end of the photonic lead such that a characteristic of the second light is modulated to encode the sensed characteristics of the predetermined tissue region.
A further aspect of the present invention is a tissue invasive photonic system. The tissue invasive photonic system includes a photonic lead having a proximal end and a distal end; a light source, in the proximal end of the photonic lead, to produce a first light having a first wavelength and a second light having a second wavelength; a wave-guide between the proximal end and distal end of the photonic lead; a bio-sensor, in the distal end of the photonic lead, to sense characteristics of a predetermined tissue region; a distal emitter, in the distal end of the photonic lead and responsive to the bio-sensor, to emit a second light having a second wavelength to proximal end of the photonic lead such that a characteristic of the second light is modulated to encode the sensed characteristics of the predetermined tissue region; a power sensor to receive the first light from the wave-guide and convert the received first light into electrical energy; and a plurality of switchable capacitors operatively connected to an output of the power sensor.
A further aspect of the present invention is a tissue invasive photonic system. The tissue invasive photonic system includes a photonic lead having a proximal end and a distal end; a light source, in the proximal end of the photonic lead, to produce a first light having a first wavelength and a second light having a second wavelength; a wave-guide between the proximal end and distal end of the photonic lead; a radiation scattering medium at the distal end of the photonic lead to receive radiation from the wave-guide; a plurality of power sensors to receive scattered radiation from the radiation scattering medium and convert the received scattered radiation into electrical energy; a bio-sensor, in the distal end of the photonic lead, to sense characteristics of a predetermined tissue region; a distal sensor, in the distal end of the photonic lead, responsive to the bio-sensor, to reflect the second light back to the proximal end of the photonic lead such that a characteristic of the second light is modulated to encode the sensed characteristics of the predetermined tissue region; and a beam splitter to direct the second light to the distal sensor.
A further aspect of the present invention is a tissue invasive photonic system. The tissue invasive photonic system includes a photonic lead having a proximal end and a distal end; a light source, in the proximal end of the photonic lead, to produce a first light having a first wavelength and a second light having a second wavelength; a first wave-guide between the proximal end and distal end of the photonic lead; a second wave-guide, having a plurality of power beam splitters therein at the distal end of the photonic lead to receive and reflect the first light from the first wave-guide; a plurality of power sensors to receive the first light from the power beam splitters in the second wave-guide and convert the received first light into electrical energy; a bio-sensor, in the distal end of the photonic lead, to sense characteristics of a predetermined tissue region; a sensor beam splitter to reflect the second light from the first wave-guide; and a distal sensor, in the distal end of the photonic lead, responsive to the bio-sensor, to receive the second light from the sensor beam splitter and to reflect the second light back to the proximal end of the photonic lead such that a characteristic of the second light is modulated to encode the sensed characteristics of the predetermined tissue region.
A further aspect of the present invention is a tissue invasive photonic system. The tissue invasive photonic system a photonic lead having a proximal end and a distal end; a light source, in the proximal end of the photonic lead, to produce a first light having a first wavelength and a second light having a second wavelength; a wave-guide between the proximal end and distal end of the photonic lead; a plurality of power sensors to receive the first light from the wave-guide and convert the received first light into electrical energy, each power sensor absorbing a fraction of the received first light; a bio-sensor, in the distal end of the photonic lead, to sense characteristics of a predetermined tissue region; a sensor beam splitter to reflect the second light from the wave-guide; and a distal sensor, in the distal end of the photonic lead, responsive to the bio-sensor, to receive the second light from the sensor beam splitter and to reflect the second light back to the proximal end of the photonic lead such that a characteristic of the second light is modulated to encode the sensed characteristics of the predetermined tissue region.
A further aspect of the present invention is a tissue invasive photonic system. The tissue invasive photonic system includes a photonic lead having a proximal end and a distal end; a light source, in the proximal end of the photonic lead, to produce a first light having a first wavelength and a second light having a second wavelength; a wave-guide between the proximal end and distal end of the photonic lead; a bio-sensor, in the distal end of the photonic lead, to sense characteristics of a predetermined tissue region; a sensor beam splitter to reflect the second light from the wave-guide; a distal sensor, in the distal end of the photonic lead, responsive to the bio-sensor, to receive the second light from the sensor beam splitter and to reflect the second light back to the proximal end of the photonic lead such that a characteristic of the second light is modulated to encode the sensed characteristics of the predetermined tissue region; a power sensor to receive the first light from the wave-guide and convert the received first light into electrical energy; and a plurality of switchable capacitors operatively connected to an output of the power sensor.